This project is conducting research on the molecular mechanisms involved in the biogenesis of functional mRNA from its high molecular weight nuclear precursor, HnRNA, in a cell-free system from Ehrlich ascites tumor cells. HnRNA has been isolated from adenovirus-infected HeLa cells 18-20 hr postinfection. Experiments are conducted to study the following areas: (1) mechanism of cleavage and transition of HnRNA (2) role of nuclear and cytoplasmic protein factors required for cleavage, processing and translation of HnRNA.